/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 25397
 * Date: 2021-11-24
 * Time: 15:01
 */
class Node{
    public int val;
    public Node next;//指向后驱
    public Node prev;//指向前驱
    public Node(int val){
        this. val=val;
    }
}

public class DoubleLinkedList {

    /*//头插
    public void addFirst(int data){

    }

    //尾插
    public void addLast(int data){

    }

    //任意位置插入,第一个节点下标为0
    public boolean addIndex(int index,int data){


    }

    //查找关键字key是否在链表中
    public boolean contains(int key){

    }

    //删除所有值为key的节点
    public void removeAllKey(int key){

    }

    //得到链表的长度
    public int size(){

    }

    //（遍历）打印链表
    public void display(){

    }

    //清空链表
    public void clear(){

    }*/
}
